Which change is associated with improved aerobic capacity as a cardiovascular adaptation?

Which change is associated with improved aerobic capacity as a cardiovascular adaptation?

• A. Decreased Blood Flow To Muscles
• B. Increased Heart Size And Stroke Volume
• C. Lower Capillary Density
• D. Reduced Oxygen Extraction

Answer: (B)

Improved aerobic capacity mainly comes from the heart becoming more efficient at delivering blood—and thus oxygen—to working muscles. Endurance training causes the heart to adapt by becoming slightly larger, especially the left ventricle, which increases stroke volume (the amount of blood ejected with each beat). With a bigger stroke volume, the heart can pump more blood per beat and maintain or even lower heart rate during activity, boosting overall cardiac output. This means more oxygen-rich blood reaches the muscles during exercise, supporting higher endurance and VO2 max. The other changes would hamper oxygen delivery or use—less blood flow, fewer capillaries, or reduced oxygen extraction—so they don’t support better aerobic capacity.

Improved aerobic capacity mainly comes from the heart becoming more efficient at delivering blood—and thus oxygen—to working muscles. Endurance training causes the heart to adapt by becoming slightly larger, especially the left ventricle, which increases stroke volume (the amount of blood ejected with each beat). With a bigger stroke volume, the heart can pump more blood per beat and maintain or even lower heart rate during activity, boosting overall cardiac output. This means more oxygen-rich blood reaches the muscles during exercise, supporting higher endurance and VO2 max. The other changes would hamper oxygen delivery or use—less blood flow, fewer capillaries, or reduced oxygen extraction—so they don’t support better aerobic capacity.